1. Field of the Invention
The present invention relates to a method of manufacturing a semiconductor device. Most particularly, the present invention relates to a method of manufacturing a liner insulating layer for a node contact hole.
2. Description of the Related Art
In order to increase the alignment window of the node contact hole, and to obtain good isolation between a node contact and a bit line, or between the node contact and the word line, a liner insulating layer is formed on a sidewall of the node contact. In the convention method, the liner insulating including a silicon nitride layer or a silicon oxide layer is required to be thick enough to provide good isolation.
The liner insulating layer is typically formed to contact a substrate comprising the above node contact, bit line, and word line. In a subsequent thermal process, defects such as lattice dislocation may easily occur due to a difference of lattice structure between the liner silicon nitride layer and the substrate. Hence, leakage occurs at the node contact. This phenomenon is more obvious for a thick liner silicon nitride layer since the larger thickness often leads to a higher stress. While the thickness of the liner silicon nitride layer is decreased to avoid the problem caused by stress, the thin liner silicon nitride layer cannot provide good isolation. Therefore, there is a trade off between the advantages of defect free and good isolation in determining the thickness of the liner silicon nitride layer.
When a liner silicon oxide layer is selected as the liner insulating layer, a thin liner silicon oxide layer is easily stripped away by a H.sub.2 O.sub.2 /NH.sub.4 OH/HF solution used to clean the node contact hole before the node contact is formed to fill the node contact hole. When the liner silicon oxide layer is thick, the step coverage of the liner silicon oxide layer is poor. Therefore, it is difficult to fill the node contact hole with node contact material.